Mechanical counters which show how much cable of an elongate hydrophone array has been played out are many and varied in design. However, like all mechanical devices, wear and corrosion affect their reliability. Electromechanical or electronic counters have proven to be more satisfactory, yet they too are susceptible to damage from corrosion, vibration, shock, etc. None of the contemporary measuring devices are adaptable to operate reliably at great ocean depths. Seismic devices with their related instrumentation are being strung out in elongate arrays for data gathering purposes. The location of the several instrumentation packages along the array with respect to a known reference point is necessary to allow a meaningful correlation of the data obtained. Hence, an accurate, reliable counter which tells how much of the array has been played out or reeled in should be provided. Presently, in the state of the art, there is a need for a pressure insensitive counter designed to measure the length of a cable deployed from a submerged winch.